1. Field of the Invention
The present invention relates to optical sensors, more specifically to filtering false detections in optical sensor data.
2. Brief Description of Related Art
One of the most common uses of optical sensors in a military setting is to detect and counter a launched ordnance as part of a threat detection system. To achieve maximum protection of the host platform, it is crucial to minimize false detections and also accurately identify the type of threat detected by the system.
Each type of launched ordnance typically emits a three-part signature having a spectral element, a spatial element, and a temporal element which is detected by the threat detection system. The spectral element is manifested as an intensity ratio of multiple spectral bands emitted by the detected signature. The spatial element is typically incorporated into spectral intensity data by way of spatial median filter and represents the size of the source within the image pixel space. A launched ordnance signature will exhibit the spatial qualities of a point source. Finally, the temporal element of a launched ordnance signature will indicate a brief “turn-on” followed by a longer, more sustained pulse and contain minimal noise.
Existing methods set thresholds in all three elements and separately filter each one to eliminate detections. First, the spatial median filter is applied to the spectral data, where it is then filtered for proper spectral ratio and point source status. Then yet another filter searches for the correct temporal signature. However, this method requires either that all of the data be filtered at least three times, taxing host platform processing resources or that false detections be allowed whenever at least one of the signature elements is satisfied.